SpaceX in the 2030s

[steveleach]

In light of the recent tweet about optimum launcher sizes (after figuring in logistics), I'd say that the next advancement isnt a "starship 2", but a cycler capable of taking standard point to point starships (with a thousand passangers packed in like sardines) and cover the life support, gravity and legroom requirements for a 4 month trip to mars.

It then replenishes it's reserves and does science for the 4 year off season in interplantary space, waiting for the next tourist season.

AIUI, you'd need a bunch of cyclers as they'd spend most of their time coasting through empty space out past Mars.

That's really not a problem though, as you need a huge fleet for the Mars flotillas and that fleet doesn't have anything to do between opportunities. Might as well use it to shuttle materials around for cycler construction.

[oldAtlas_Eguy]

I was merely trying to point out that SpaceX has been doing an architectural change that then did a 5X drop in cost 4/kg after the previous system level design had been out for 10 years. And that after the it had been out for 5 years that a significant performance upgrade ending up with a 2x drop in cost $/kg also occurred. Such that in early 2030's as in 2021 or 2022 a new system would emerge. My take was a simple 2X diameter increase from 9m to 18m. A 4 to 5X performance increase. Such an increase would probably contribute tremendously to that 5X cost drop since about the same amount of manpower and infrastructure costs would be involved even though the vehicle is effectively 5X larger in mass and volume. Such that cost per launch would practically be close to the same as that of the 9m Starship version.

There may be other innovations that occur at that time as well regarding BEO travel improvements that greatly reduce the costs of travel to the Moon or Mars. At least in the standpoint of cost per m3 or volume per passenger. Making travel more comfortable and luxurious like that of a cruise ship vs a packed widebody aircraft for BEO travel.

SpaceX involvement in the cycler or something similar may or may not occur. But SpaceX involvement in getting from surface to orbit and back again is still likely to be the premiere service.

In a period of 10 years SpaceX has gone from in 2011 a total of just 2 launches of F9 (2010 and 2011). To in 2021 what looks to be 40 launches this year.

[RyanC]

Casey Handmer has a good piece on why space-based solar isn't viable, and I'd recommend you read it (some of the numbers are mildly out of date, but the argument is still solid).

The Department of Defense is once again looking into portable nuclear reactors as an option for supplying remote places, after a 50+ year interruption. That's rather significant since for a long time, nuclear anything was verboten.

Link to article in 2009

Basically, in 2009, DOD was paying $400/gallon to get fuel into Afghanistan.

From searching around, a small generator at full load would generate about 12.5 KWH of electricity from a gallon of diesel, while a big generator would generate about 14 KWH of electricity from a gallon.

So basically, at an average of 13.25 kWh/gallon and $400/gallon transport costs; it was costing DOD about $30+ dollars a kWh to generate electricity in Afghanistan.

Bagram Airbase, basically the hub for all air movement in and out of Afghanistan, with 40,000~ troops at it's peak, had a 56 MW gas turbine powerplant system.

A typical Forward Operating Base in Afghanistan had a 30 kW generator running 24/7, but with an average load of 5 kW, for 54 gallons of fuel burned per day.

So it basically cost DOD $21,600 per day to run the lights at a FOB in Afghanistan.

Back in 1994, the Japanese came up with the SPS 2000 space based solar system concept.

http://www.spacefuture.com/archive/conceptual_study_of_a_solar_power_satellite_sps_2000.shtml
http://www.spacefuture.com/archive/sps_2000_and_its_internationalisation.shtml
https://www.esa.int/gsp/ACT/doc/POW/GSP-RPT-SPS-0503%20LBST%20Final%20Report%20Space%20Earth%20Solar%20Comparison%20Study%20050318%20s.pdf

It was to be a 250,000 kg satellite with 9 hectares (90,000 m2) of solar panels in an equilateral triangular prism generating 10 MW with a specific weight of 25 grams per watt. Actual deliverable power was to be about 100 kW continuous, and multiple satellites would have been needed to keep power going.

If we scaled that down to a 50 kW (deliverable) satellite to power a FOB, we'd end up with a 125-tonne satellite.

Simply placing that much mass in orbit would cost:

$5,590.875 Million with STS ($44,727/kg)
$2,074.875 Million with Atlas V 421 ($16,599/kg)
$693.25 Million with Vulcan VC2 ($5,546/kg)
$478 Million with Falcon 9 FT (ASDS) ($3,824/kg)
$293.875 Million with Falcon 9 Heavy (Exp) ($2,351/kg)
$209 Million with New Glenn ($1,672/kg)
$50.625 Million with Starship (ASDS) ($405/kg)
$5 Million with Hypothetical Future ($40/kg)

To put all these costs into perspective; recently the LRIP FY2021 Lot 5 contract was awarded to Sikorsky for nine CH-53K King Stallion helicopters at $878.7M total ($97.6M each).

Elon's opposition to Space Based Solar is more of a "I don't have enough time in the world" thing -- because to bring SBS to fruition would take a lot of engineering manhours to bring the entire appartus to a TRL high enough for launch -- and he's got so much other things that need to be done with SpaceX that he's not going to waste engineering manpower on a SpaceX/Tesla/SolarCity power satellite.

If, however, someone signed a contract with SpaceX to place a power satellite in orbit, he'd be more than happy to do it for them.

[freddo411]

Casey Handmer has a good piece on why space-based solar isn't viable, and I'd recommend you read it (some of the numbers are mildly out of date, but the argument is still solid).

The Department of Defense is once again looking into portable nuclear reactors as an option for supplying remote places, after a 50+ year interruption. That's rather significant since for a long time, nuclear anything was verboten.

Link to article in 2009

Basically, in 2009, DOD was paying $400/gallon to get fuel into Afghanistan.

From searching around, a small generator at full load would generate about 12.5 KWH of electricity from a gallon of diesel, while a big generator would generate about 14 KWH of electricity from a gallon.

So basically, at an average of 13.25 kWh/gallon and $400/gallon transport costs; it was costing DOD about $30+ dollars a kWh to generate electricity in Afghanistan.

Bagram Airbase, basically the hub for all air movement in and out of Afghanistan, with 40,000~ troops at it's peak, had a 56 MW gas turbine powerplant system.

A typical Forward Operating Base in Afghanistan had a 30 kW generator running 24/7, but with an average load of 5 kW, for 54 gallons of fuel burned per day.

So it basically cost DOD $21,600 per day to run the lights at a FOB in Afghanistan.

Back in 1994, the Japanese came up with the SPS 2000 space based solar system concept.

http://www.spacefuture.com/archive/conceptual_study_of_a_solar_power_satellite_sps_2000.shtml
http://www.spacefuture.com/archive/sps_2000_and_its_internationalisation.shtml
https://www.esa.int/gsp/ACT/doc/POW/GSP-RPT-SPS-0503%20LBST%20Final%20Report%20Space%20Earth%20Solar%20Comparison%20Study%20050318%20s.pdf

It was to be a 250,000 kg satellite with 9 hectares (90,000 m2) of solar panels in an equilateral triangular prism generating 10 MW with a specific weight of 25 grams per watt. Actual deliverable power was to be about 100 kW continuous, and multiple satellites would have been needed to keep power going.

If we scaled that down to a 50 kW (deliverable) satellite to power a FOB, we'd end up with a 125-tonne satellite.

Simply placing that much mass in orbit would cost:

$5,590.875 Million with STS ($44,727/kg)
$2,074.875 Million with Atlas V 421 ($16,599/kg)
$693.25 Million with Vulcan VC2 ($5,546/kg)
$478 Million with Falcon 9 FT (ASDS) ($3,824/kg)
$293.875 Million with Falcon 9 Heavy (Exp) ($2,351/kg)
$209 Million with New Glenn ($1,672/kg)
$50.625 Million with Starship (ASDS) ($405/kg)
$5 Million with Hypothetical Future ($40/kg)

To put all these costs into perspective; recently the LRIP FY2021 Lot 5 contract was awarded to Sikorsky for nine CH-53K King Stallion helicopters at $878.7M total ($97.6M each).

Elon's opposition to Space Based Solar is more of a "I don't have enough time in the world" thing -- because to bring SBS to fruition would take a lot of engineering manhours to bring the entire appartus to a TRL high enough for launch -- and he's got so much other things that need to be done with SpaceX that he's not going to waste engineering manpower on a SpaceX/Tesla/SolarCity power satellite.

If, however, someone signed a contract with SpaceX to place a power satellite in orbit, he'd be more than happy to do it for them.

Great use of real numbers in this post, but you didn't do the math to come to the final conclusion.

 $21k * 365 * 10 years = $77 million for 10 years of electricity at a FOB in Afghanistan
Launch cost would be roughly $300 million on FH.   (and if I understand things correctly, more than one instance of these would be needed).

So it looks like the business case for space based solar doesn't beat the price of diesel in afghanistan.

[oldAtlas_Eguy]

Casey Handmer has a good piece on why space-based solar isn't viable, and I'd recommend you read it (some of the numbers are mildly out of date, but the argument is still solid).

The Department of Defense is once again looking into portable nuclear reactors as an option for supplying remote places, after a 50+ year interruption. That's rather significant since for a long time, nuclear anything was verboten.

Link to article in 2009

Basically, in 2009, DOD was paying $400/gallon to get fuel into Afghanistan.

From searching around, a small generator at full load would generate about 12.5 KWH of electricity from a gallon of diesel, while a big generator would generate about 14 KWH of electricity from a gallon.

So basically, at an average of 13.25 kWh/gallon and $400/gallon transport costs; it was costing DOD about $30+ dollars a kWh to generate electricity in Afghanistan.

Bagram Airbase, basically the hub for all air movement in and out of Afghanistan, with 40,000~ troops at it's peak, had a 56 MW gas turbine powerplant system.

A typical Forward Operating Base in Afghanistan had a 30 kW generator running 24/7, but with an average load of 5 kW, for 54 gallons of fuel burned per day.

So it basically cost DOD $21,600 per day to run the lights at a FOB in Afghanistan.

Back in 1994, the Japanese came up with the SPS 2000 space based solar system concept.

http://www.spacefuture.com/archive/conceptual_study_of_a_solar_power_satellite_sps_2000.shtml
http://www.spacefuture.com/archive/sps_2000_and_its_internationalisation.shtml
https://www.esa.int/gsp/ACT/doc/POW/GSP-RPT-SPS-0503%20LBST%20Final%20Report%20Space%20Earth%20Solar%20Comparison%20Study%20050318%20s.pdf

It was to be a 250,000 kg satellite with 9 hectares (90,000 m2) of solar panels in an equilateral triangular prism generating 10 MW with a specific weight of 25 grams per watt. Actual deliverable power was to be about 100 kW continuous, and multiple satellites would have been needed to keep power going.

If we scaled that down to a 50 kW (deliverable) satellite to power a FOB, we'd end up with a 125-tonne satellite.

Simply placing that much mass in orbit would cost:

$5,590.875 Million with STS ($44,727/kg)
$2,074.875 Million with Atlas V 421 ($16,599/kg)
$693.25 Million with Vulcan VC2 ($5,546/kg)
$478 Million with Falcon 9 FT (ASDS) ($3,824/kg)
$293.875 Million with Falcon 9 Heavy (Exp) ($2,351/kg)
$209 Million with New Glenn ($1,672/kg)
$50.625 Million with Starship (ASDS) ($405/kg)
$5 Million with Hypothetical Future ($40/kg)

To put all these costs into perspective; recently the LRIP FY2021 Lot 5 contract was awarded to Sikorsky for nine CH-53K King Stallion helicopters at $878.7M total ($97.6M each).

Elon's opposition to Space Based Solar is more of a "I don't have enough time in the world" thing -- because to bring SBS to fruition would take a lot of engineering manhours to bring the entire appartus to a TRL high enough for launch -- and he's got so much other things that need to be done with SpaceX that he's not going to waste engineering manpower on a SpaceX/Tesla/SolarCity power satellite.

If, however, someone signed a contract with SpaceX to place a power satellite in orbit, he'd be more than happy to do it for them.

Great use of real numbers in this post, but you didn't do the math to come to the final conclusion.

 $21k * 365 * 10 years = $77 million for 10 years of electricity at a FOB in Afghanistan
Launch cost would be roughly $300 million on FH.   (and if I understand things correctly, more than one instance of these would be needed).

So it looks like the business case for space based solar doesn't beat the price of diesel in afghanistan.

Or $50M on Starship. So for this case Starship makes it possible barely. But again Musk is unlikely to spend his money on it with such a narrow margin for better than current.

[Scintillant]

Casey Handmer has a good piece on why space-based solar isn't viable, and I'd recommend you read it (some of the numbers are mildly out of date, but the argument is still solid).

The Department of Defense is once again looking into portable nuclear reactors as an option for supplying remote places, after a 50+ year interruption. That's rather significant since for a long time, nuclear anything was verboten.

Link to article in 2009

Basically, in 2009, DOD was paying $400/gallon to get fuel into Afghanistan.

From searching around, a small generator at full load would generate about 12.5 KWH of electricity from a gallon of diesel, while a big generator would generate about 14 KWH of electricity from a gallon.

So basically, at an average of 13.25 kWh/gallon and $400/gallon transport costs; it was costing DOD about $30+ dollars a kWh to generate electricity in Afghanistan.

Bagram Airbase, basically the hub for all air movement in and out of Afghanistan, with 40,000~ troops at it's peak, had a 56 MW gas turbine powerplant system.

A typical Forward Operating Base in Afghanistan had a 30 kW generator running 24/7, but with an average load of 5 kW, for 54 gallons of fuel burned per day.

So it basically cost DOD $21,600 per day to run the lights at a FOB in Afghanistan.

Back in 1994, the Japanese came up with the SPS 2000 space based solar system concept.

http://www.spacefuture.com/archive/conceptual_study_of_a_solar_power_satellite_sps_2000.shtml
http://www.spacefuture.com/archive/sps_2000_and_its_internationalisation.shtml
https://www.esa.int/gsp/ACT/doc/POW/GSP-RPT-SPS-0503%20LBST%20Final%20Report%20Space%20Earth%20Solar%20Comparison%20Study%20050318%20s.pdf

It was to be a 250,000 kg satellite with 9 hectares (90,000 m2) of solar panels in an equilateral triangular prism generating 10 MW with a specific weight of 25 grams per watt. Actual deliverable power was to be about 100 kW continuous, and multiple satellites would have been needed to keep power going.

If we scaled that down to a 50 kW (deliverable) satellite to power a FOB, we'd end up with a 125-tonne satellite.

Simply placing that much mass in orbit would cost:

$5,590.875 Million with STS ($44,727/kg)
$2,074.875 Million with Atlas V 421 ($16,599/kg)
$693.25 Million with Vulcan VC2 ($5,546/kg)
$478 Million with Falcon 9 FT (ASDS) ($3,824/kg)
$293.875 Million with Falcon 9 Heavy (Exp) ($2,351/kg)
$209 Million with New Glenn ($1,672/kg)
$50.625 Million with Starship (ASDS) ($405/kg)
$5 Million with Hypothetical Future ($40/kg)

To put all these costs into perspective; recently the LRIP FY2021 Lot 5 contract was awarded to Sikorsky for nine CH-53K King Stallion helicopters at $878.7M total ($97.6M each).

Elon's opposition to Space Based Solar is more of a "I don't have enough time in the world" thing -- because to bring SBS to fruition would take a lot of engineering manhours to bring the entire appartus to a TRL high enough for launch -- and he's got so much other things that need to be done with SpaceX that he's not going to waste engineering manpower on a SpaceX/Tesla/SolarCity power satellite.

If, however, someone signed a contract with SpaceX to place a power satellite in orbit, he'd be more than happy to do it for them.

Great use of real numbers in this post, but you didn't do the math to come to the final conclusion.

 $21k * 365 * 10 years = $77 million for 10 years of electricity at a FOB in Afghanistan
Launch cost would be roughly $300 million on FH.   (and if I understand things correctly, more than one instance of these would be needed).

So it looks like the business case for space based solar doesn't beat the price of diesel in afghanistan.

Or $50M on Starship. So for this case Starship makes it possible barely. But again Musk is unlikely to spend his money on it with such a narrow margin for better than current.

Starship still doesn't make the numbers work out because the military could just buy regular solar panels. Need 125kW at a FOB? Just buy 10 of these solar power containers, ship them via regular methods, and install them, for a total cost of about $1 million. Worried about capacity factors and nighttime energy supply? Just buy another 10 containers and a container or two of batteries, or just keep your current generators as backup (the attached USMC study is a good example, 56% fuel savings from installing a 5kW PV+batteries system).

The point is, even if my cost estimate is off by a factor of 50, it's still cheaper than space-based solar. On-planet solar is just that cheap, and getting cheaper every year. Space-based solar is unlikely to work out.

[RyanC]

Great use of real numbers in this post, but you didn't do the math to come to the final conclusion.

 $21k * 365 * 10 years = $77 million for 10 years of electricity at a FOB in Afghanistan

Thanks for using the numbers I provided to provide a "minimum cost closing" case for Space-Based Solar Power in a military context. So effectively, a satellite has to be built AND delivered to an operational orbit for around that cost.

The military might fund it if it was 25-30% more expensive than that baseline cost (96M to 100M) because that's still within the range of cost for a single CH-53K heavy lift helo ($97.6M); and justifiable within DOD budget for "experimental" work; because while there's a monetary cost to providing fuel, there's also a human cost -- people need to escort fuel convoys, and they get attacked/killed on fuel convoys.

[IainMcClatchie]

I don't see how SPS installations with less than a gigawatt or so can be made to work.

The SPS pretty much has to be in geosynchronous orbit.  The transmission frequency has some flexibility, but it's probably either 2.4 or 5.0 GHz: anything higher leads to fairly significant losses piling up in the RF amplifier, the atmosphere, and the rectenna diode.

So that says that the diameter of the ground and SPS antennas have to be something like 2.4 km across.  It's diffraction limited, and has nothing to do with power.  One antenna can get smaller if the other gets bigger.  The PV area will be close to the transmitting antenna area, and at 30% conversion efficiency that's 1.8 GW.  If the DC->RF->DC beam transmission is 50% efficient, you end up with about a gigawatt on the ground.

A gigawatt is quite a bit for a military base, even a big one, unless you are synthesizing fuel on site for jets, in which case it's quite reasonable (and wow you have a big chemical plant / target on base).

[oldAtlas_Eguy]

SPS power generation for use on Earth may never reach an economic business case. But will reach it for use in space as a source for various usages where the use of beamed power rectennas over that of solar cells result in a lower mass for electric propulsion tugs, etc. In space the ERP at the Rectenna can be much higher per m^2 than for a solar array. Or even the use of laser beamed power to up the incidence level on a solar array to increase it's power output per kg of mass. For tugs it is all about the dry weight.

[Jim]

Thanks for using the numbers I provided to provide a "minimum cost closing" case for Space-Based Solar Power in a military context.

It never closes.  The ground infrastructure is too big and vulnerable.

[Jim]

I would bet you $100 that right now, Space X has a private "Raiders of the Lost Ark" Division set up to evaluate all sorts of crazy stuff for "breakthrough technologies", ranging from "can we commercialise VASMIR" to "EM Drive".

I would also bet you $25 that SpaceX has actually flown some of these potential technologies in orbit, either on Starlink satellites themselves, or on Starlink-only Falcon 9 Upper Stages (the advantages of having your own internal payloads is that you can do risks with them that no paying customer would dare allow).

You lose on both

[IainMcClatchie]

SPS power generation for use on Earth may never reach an economic business case. But will reach it for use in space as a source for various usages where the use of beamed power rectennas over that of solar cells result in a lower mass for electric propulsion tugs, etc. In space the ERP at the Rectenna can be much higher per m^2 than for a solar array. Or even the use of laser beamed power to up the incidence level on a solar array to increase it's power output per kg of mass. For tugs it is all about the dry weight.

The diffraction problem is pretty bad using RF.  You aren't limited by watts/m^2.  If the tug's distance to the solar array is any significant fraction of an orbital diameter, you'll need km-scale antennas.  Atmospheric absorption isn't a problem in orbit-to-orbit beamed power, but you still can't go much above 5 GHz or you'll lose too much efficiency in the rectenna diode.

The alternative is lasers.  These have bad efficiency and truly awful power to weight and price to power ratios, but they can operate in the IR or visible band and so don't have significant diffraction in space.  Laser illumination of PV cells optimized to convert the laser's wavelength can deliver amazing efficiency -- better than 90% at the receive end.

The trouble with ground-based lasers for powering things in space (or even high flying aircraft) is scattering by the atmosphere and that terrible cost per watt.

I'm enthusiastic about the prospect of space-based PV power beamed to the ground, but it's definitely got a nasty minimum size problem.

[oldAtlas_Eguy]

SPS power generation for use on Earth may never reach an economic business case. But will reach it for use in space as a source for various usages where the use of beamed power rectennas over that of solar cells result in a lower mass for electric propulsion tugs, etc. In space the ERP at the Rectenna can be much higher per m^2 than for a solar array. Or even the use of laser beamed power to up the incidence level on a solar array to increase it's power output per kg of mass. For tugs it is all about the dry weight.

The diffraction problem is pretty bad using RF.  You aren't limited by watts/m^2.  If the tug's distance to the solar array is any significant fraction of an orbital diameter, you'll need km-scale antennas.  Atmospheric absorption isn't a problem in orbit-to-orbit beamed power, but you still can't go much above 5 GHz or you'll lose too much efficiency in the rectenna diode.

The alternative is lasers.  These have bad efficiency and truly awful power to weight and price to power ratios, but they can operate in the IR or visible band and so don't have significant diffraction in space.  Laser illumination of PV cells optimized to convert the laser's wavelength can deliver amazing efficiency -- better than 90% at the receive end.

The trouble with ground-based lasers for powering things in space (or even high flying aircraft) is scattering by the atmosphere and that terrible cost per watt.

I'm enthusiastic about the prospect of space-based PV power beamed to the ground, but it's definitely got a nasty minimum size problem.

As I mentioned and Jim has as well the business cases even for laser to ground PV is likely to not close. Back at the advent of the SPS idea. The business case closed because there was not a more easier and competitive solution that used the same land area with about the same daily power output. It is primarily the efficiencies and very low cost of the PV cells that has caused this. Which was not the case in the 1980's. Where the low efficiencies and high cost of PV cells required some method to increase the overall efficiency of the system for same land area usage.

Now the beamed power concept may have some usage in the electric tug market that has yet to emerge. But it too may be surpassed by other solutions that will be cheaper system wise for same capability that are as yet not possible.

A NOTE here is that Starship itself may be both an enabler and the ultimate killer of the SPS idea.

[RedLineTrain]

The only other alternative to improve $/kg is moving beyond chemical rockets entirely (build a space elevator or a giant railgun or some other sci-fi thing), but that's not a "Starship 2" -- or a serious topic for the next decade.

I would bet you $100 that right now, Space X has a private "Raiders of the Lost Ark" Division set up to evaluate all sorts of crazy stuff for "breakthrough technologies", ranging from "can we commercialise VASMIR" to "EM Drive".

I would also bet you $25 that SpaceX has actually flown some of these potential technologies in orbit, either on Starlink satellites themselves, or on Starlink-only Falcon 9 Upper Stages (the advantages of having your own internal payloads is that you can do risks with them that no paying customer would dare allow).

Musk's marginal propensity to spend money unnecessarily is approximately zero.

[RyanC]

I don't see how SPS installations with less than a gigawatt or so can be made to work.

The SPS pretty much has to be in geosynchronous orbit.

The Japanese SPS-2000 study I've been citing uses a 1,100 km orbit.

This cuts down the time of power a single satellite can deliver to 200 seconds (3.33 minutes) during an orbital period of 100~ minutes for a single specific location along it's orbital plane. It does however, reduce the size of the rectenna from 2.4 km to about 1~ km.

It's basically SPS-Starlink -- meaning if you want to deliver continuous power to a specific location on earth, you need about 34~ satellites in an orbital train, one after another.

Also, while doing "shower thoughts", I had a thought and checked it up on the documentation available for me on SPS-2000:

http://www.spacefuture.com/archive/sps_2000_and_its_internationalisation.shtml

The intensity at the center of the SPS 2000 microwave beam is only 10 W/sqm, which is the internationally accepted safety level for continuous wave radiation at 2.45 GHz, as used in microwave ovens.[/b]

...

By contrast, it is proposed that future commercial Systems should have intensities as high as several hundred W/sqm.

Since the downlink of SPS-2000 is 100 kW, that 10 W/m2 requirement mandates an antenna size of 10,000 m2; or roughly a 113~ m diameter antenna.

I assume the other 887~ m of diameter in the SPS-2000 antenna (a safety factor of 7.84x) is for safety margin reasons for people/livestock which may inadvertently wander under an operating rectenna; and also to make a cheap rectenna that can be easily maintained, being a wire mesh some 2 to 3 meters above the ground on poles.

Some quick calculations on the AN/SPY-1A for AEGIS ships (3 to 4 GHz, 12 m2 antenna area, peak power of 5 MW) gives me an intensity of 416.6 kW/m2.

This is in line with a 2004 DOD report (Defense Science Board Task Force on Contributions of Space Based Radar to Missile Defense) (https://dsb.cto.mil/reports/2000s/ADA428771.pdf)

"For reference, the average radiated power aperture for the Aegis radar system is 485 kW/m2"

If we assume the downlink station can handle 300 kW/m2; that means you'd only need an antenna of 0.33 m2 which would be 0.64 m in diameter.

If we applied the same "safety" factor of 7.84x, we'd end up with a 5m diameter antenna, -- bigger than an AN-SPY-1B/D antenna (which is 3.7m diameter).

Issues With This

1.) The Receiving Station would be expensive -- I think the big reason everyone goes with low power rectennas is that they can be cheaply built; and acquiring more land is not a big deal, allowing you to reduce the accuracy margins of the orbital SPS elements. Also, a certain percentage of the downlinked power would have to be spent in actively cooling the receiving station's RF elements.

2.) AESA-type systems would have to be commercialized in order to deal with the continuous stream of satellites coming in overhead every 3 minutes and switching the beam from one satellite to the next. This is something that Starlink has solved on a small, communications scale system.

Biggest Issue of All

Is that it would run afoul of space weaponisation agreements. Being able to direct 100 kW of RF energy precisely onto a 5m2 area from orbit would be a literal "death ray" from space -- you could probably knock out the electrical systems of vehicles; among other things.

Implications Elsewhere

This was a rabbit hole that was interesting to run into; even if it wasn't totally related to Space X in the 2030s.

Given that the 92 millinewton ion engine on Deep Space 1 needed 2.1 kW of power to operate, one might wonder about designing a "dual thrust" electrical engine that could operate in beamed power "high thrust" mode close to Earth, before switching to self-powered (onboard solar) "cruise thrust" beyond Earth's influence.

[high road]

I think SpaceX has done very, very well. But I know from 'the horses mouth' anecdotes that they have 'burned out' a lot of personnel as much as they have cash to get there. I like the ambitiousness of the 'Starship' project but often feel that SpaceX should have tried an intermediate technological and engineering step halfway between Falcon Heavy and BFR before going the Starship route. Before the big, 2016 reveal of the BFR/Starship program, I was nearly convinced that Elon was going to 'supersize' the Dragon spacecraft and upgrade the Falcon Heavy with a better upper stage - all with the intention to do a somewhat 'Mars Direct' reconnaissance mission(s) to Mars first with 4-to-6 person crews.

They could have demonstrated in space Cryo propellant transfer and propellant ISRU on the Martian surface before moving onto the really big vehicles we are seeing prototyped today. They are, in a sense, biting off almost more than they can chew with the current paradigm they are pursuing. It could all fail and falter; but I sure hope it doesn't.

If such an approach does not reduce the cost of access to space/Mars significantly, that would be a guarantee for things to falter. If access to space is reduced by a ship capable of launching 100 tons for the price of an F9, others can continue where SpaceX stops. And 'stop making progress' would be the worst case scenario, as even a bankrupt SpaceX would find investors to keep launching those rockets.

[high road]

SpaceX in the 2030’s? Why all the wild speculation? Just go with what Elon has said instead. 1000 Starship launches per year.

That dominates everything else. (And makes everything else possible).

So that's not a wild fantasy? 😁

I mean, do we really trust the predictions of a guy who in the same interview says he will send a 100 people to Mars for 500k a person, on a vehicle that can land a 100 tons on Mars, and the return trip is 'essentially free' because they need the rockets back, but prepackaged crack can't be braught back at a profit?

Either his predictions don't have a good grasp of the scale of what he's talking about (which does not detract from SpaceX' amazing achievements or chance of success, it's just like experts saying people will never need more than an x kilobyte computer), or he has a crack supplier who sells at 0.5 to 5 dollars per gram, depending how you calculate it. That's bound to impede on your ability to calculate :p

[IainMcClatchie]

Ryan, thanks for the interesting link to the SPS 2000 study.  I have not before read about a design for a LEO SPS.  The usual problem there is that, like LEO comsats, the satellites don't get very high utilization, which drives up cost.

Here is a 2007 study by the Union Radio Scientifique Internationale that I've found useful: https://www.ursi.org/files/WhitePapers/WPSPS-ReportMin.pdf

The 10 W/m^2 limit applies to 5.8 GHz radiation.  2.45 GHz radiation has a 50 W/m^2 human safety limit.  Most gigawatt-class designs are well over this limit, but the report seems optimistic that the beam can be designed to be Gaussian, falling off in intensity so that outside of the rectenna it is always under the human safety limit, even assuming various beam control failures.

For a gigawatt-class SPS system which keeps beam flux less than solar insolation, the rectenna has to be large enough that diffraction from geosynchronous orbit is not a problem.  It can actually be a benefit, since it passively limits beam intensity to something less than a death ray.

I assume the other 887~ m of diameter in the SPS-2000 antenna (a safety factor of 7.84x) is for safety margin reasons for people/livestock which may inadvertently wander under an operating rectenna

I suspect that 1 km diameter is to catch a beam which is broadening through diffraction.  For a 1100 km orbit, I'd assume a max slant range of 2000 km.  Getting the beam into a 1 km aperture at 2.45 GHz would require a transmit aperture 300 m across.  I think that's the proposed size of the satellite.

[high road]

Based on Elon's age (49) and the lifecycle of the current Falcon rocket family (16~ years from 2002 and Falcon 1 to 2018 and Falcon 9 Block 5); Starship is likely to be Elon's Last Big Thing (TM); if we assume that it follows the same active life.

If we assume that serious work on Starship began in 2016; a sixteen year lifecycle carries us out to 2032; where Elon will be 61/62 years old.

Thats 2002-2008 for F1 and 2008/2009 to 2018 for F9/FH/Crew Dragon if we count the latter three as F9 reaching its complete application. So 6 years, then 10 years. Given that SpaceX could not divert massive resources to Starship prior to 2018, a ten year life cycle would put you at 2028. So the 'last big thing' for Musk will be Mars development.

At that age; Elon only has about five to eight years left for the next iterative cycle in SpaceX history before he's 70 and starts to slow down and lose mental flexibility.

Hardly. He'll be an ever more insufferable person, no doubt. But once Starlink is generating money and Starship is launching cargo, age and mental flexibility will not be such important factors anymore. Setting up shop on Mars takes time. The biggest risk might be that his demand for continued progress eventually kills people on Mars or burns through Starlink revenues too fast, but even that is harldly inevitable.

It's plausible to assume that SpaceX will be launching 100 tonne payloads twice a day from Boca Chica/KSC for 230 days each year; placing 46,000 tonnes in LEO each year with Starship at that point.

for which paying customers?

While it's possible for SpaceX to design a UltraHeavy (basically think of UH as a notational DC-4 to Starship/SH's DC-3); I think SpaceX will be focused on fully-space only cycler designs at this point, along with various internal projects supporting commercial outposts in LEO, lunar outposts...and of course, the SpaceX Mars Outpost/Colony.

Musk's city-on-Mars plans are not enough for you, huh? But I agree SpaceX might dabble in all those things, if they have partners or paying customers.

While they're about to dominate the space launch business with F9 Block 5 and soon Starship, there's nothing "secret sauce" about them. Anyone who's smart and nimble enough can move up through the market chain and develop into a competitor to SpaceX for the launch market -- such as Rocket Lab (and Blue Origin if they can ever get their internal problems sorted).

Elon calls it 'the moat': continuous improvement. SpaceX churns out improvements to their launch vehicle designs faster than their competitors. That's the secret sauce. Until others successfully reuse their rockets, they have quite the secret sauce at the moment. And why the future tense with 'dominate'? They launch twice as often as the next most proliferous launcher, Starlink not included. And disregarding Chinese and Russian launchers, because those launches will continue to exist even if Starship launches for pennies per kg.

D.) The development of SpaceX suits for Commercial Crew. They could have contracted out to David Clark or Oceaneering to have suits made; but they did that all in house. Now they have teams capable of designing space suits for whatever needs SpaceX will have in the future; or for others.

A flight suit =/= an EVA suit. An EVA suit =/= a Mars suit. And a Mars suit =/= a Lunar suit. All different things with completely different requirements. Of the four, the flight suit has the least commonalities.

[high road]

Long post, but to sum it up, I believe SpaceX in the 2030s will inadvertently end up enabling the Bezos vision of the future but the Mars vision will wither to just being at least flags and footprints, at most, supplying some government bases with people and cargo. The amount of people who will have been in space by the end of that decade will likely
number in the 1000s. That will sound like a depressing vision to some, but I actually think its great and a giant leap
from what we've had for the past 50 years.

Agree that SpaceX will enable the vision of Jeff Bezos. But with Mars as a necessary step on that path. Mars is the easiest place to learn how to live in a closed environment with mostly closed circuit habitats. Once we have mastered Mars, the path to expand outward into the asteroid belt and beyond is open, when nuclear propulsion becomes widely available.

I have said before: If the interplanetary fairy granted me one wish for a planet to settle, it would look very much like Mars. Hard, but not too hard.

At some point there will be a deviation between what the Government want and is prepared to pay for and what SpaceX want and then we will really know what SpaceX is about. I'm convinced that at that point SpaceX will step up to the mark to fill the gap, whatever the cost to the company in order to make humanity a multi-planet species.

The ever widening gap between what the government is willing to pay and what SpaceX is willing to do to fill the gap, can be seen in the Commercial Cargo, Commercial Crew, and HLS programmes. No need for future tenses, although much more will indeed be needed, which is why SpaceX is willing to fill up that gap with Starlink revenue. Expect those trends to continue.

The only other alternative to improve $/kg is moving beyond chemical rockets entirely (build a space elevator or a giant railgun or some other sci-fi thing), but that's not a "Starship 2" -- or a serious topic for the next decade.

I would bet you $100 that right now, Space X has a private "Raiders of the Lost Ark" Division set up to evaluate all sorts of crazy stuff for "breakthrough technologies", ranging from "can we commercialise VASMIR" to "EM Drive".

I would also bet you $25 that SpaceX has actually flown some of these potential technologies in orbit, either on Starlink satellites themselves, or on Starlink-only Falcon 9 Upper Stages (the advantages of having your own internal payloads is that you can do risks with them that no paying customer would dare allow).

I wouldn't be suprised that an ever growing number of such side projects is what is slowing Blue Origin down, whereas SpaceX tends to kill projects that don't fit in the roadmap anymore, or that can't be proven viable by fast prototyping.